DAMAGE CAUSED BY ATMOSPHERIC PRECIPITATIONS. 31 



means are not practicable, the bent poles are cut back to the place 

 where the bend occurs, so as to restore the canopy by means of 

 the shoots then made from the bole ; or the damaged patches are 

 simply coppiced, and canopy is formed for itself by the new shoots 

 that spring from the stool. In thickets of conifers the choice 

 rests only between the clearing of the patches that have been 

 pressed down and the planting up of the blanks with quick-growing 

 species, or, when the damaged patches are small, and the crop has 

 already attained considerable growth, underplan ting with shade-bear- 

 ing species (Beech, Spruce, Silver Fir), in order to protect the soil. 1 

 Underplanting of broken pole-forests of Pine with shade-bearing 

 species is also highly recommendable ; all gaps and blanks in older 

 crops which are not intended to be utilised till some considerably 

 later period, but in which there is danger of the soil becoming 

 over-grown with rank weeds and thus deteriorating, should like- 

 wise be filled up with one or other of these species. A choice should 

 of course be made of that most likely to suit the soil and situation. 

 After any such calamity, particular attention should be paid by 

 the forester to the injurious insects, whose increase is excep- 

 tionally favoured through the large quantity of dead, dying, and 

 sickly growth, green stumps, &c. Against these, measures should 

 be adopted as early as possible. 



20. Damage done ly Avalanches or Snowslips. 



In the woodland regions of mountainous tracts great damage 

 can be done in the well-known form of avalanches, particularly 

 by such, often of enormous extent, as are formed at the time of the 

 melting of the snow, by the gradual descent of the snow-masses 

 > as they become heavier ; owing to the setting in of thaw, they 

 | slip down the smooth steep slopes gradually at first, but rapidly 

 I increase in size to such an extent as to carry away everything 

 I opposing their progress, and to destroy woodlands lying in their 

 : downward course. Innumerable avalanches annually glide harm- 

 lessly down the same well-defined channels, and damage is only 

 I done when new courses are opened out. In many mountainous 

 ; regions woodlands are maintained chiefly as protective forests, 

 ! with the object of preventing the formation and occurrence of 



1 Weymouth Pine, and Nordmann's and Douglas Firs can also often be advan- 

 tageously used for this purpose, as, besides being of rapid growth, they can bear a 

 ; moderate shade. 



